Active matrix organic light emitting diode (AMOLED) has been recognized as a promising display of the next generation to replace the liquid crystal display (LCD). However, with the consumers' increasing consumption level, display products with a high resolution have become prevailing. AMOLED products with a high resolution are difficult to compete with LCD, because the organic layer structures of the organic light emitting display are generally fabricated by a mask evaporation method which has problems such as malposition, low qualified rate, incapacity to emit light in a smaller area and incapacity to accurately control defects in the evaporation region, and thus fails to meet the requirement of high resolution display under rapid development. Meanwhile, the resolution of the organic light-emitting layer fabricated in a printing method rather than the mask evaporation method is extremely limited. Therefore, AMOLED products with a high resolution face serious problems of high technical difficulty, low qualified rate and high commodity price.
Quantum dots (QDs) are also called as nanocrystals, and are nanoparticles consisting of elements from Groups II-VI or Groups III-V. The particle diameter of quantum dots generally ranges from 1 nm to 20 nm. Because electrons and holes are subjected to quantum confinement, a continuous band structure changes into a discrete band structure and QDs may emit fluorescence after being excited.
With the development of quantum dot technologies, in-depth research on electroluminescent quantum dot light emitting diodes has been conducted. Quantum efficiency is increasingly improved and has basically reached an industrialization level. Further adopting new processes and technologies to realize industrialization has become a future trend. In prior arts, in order to improve the resolution of an OLED, line width in a mask process is required to be reduced for an OLED evaporation mask, and a higher precision print nozzle is required. Such requirements are difficult to be met in a mass production process. Accordingly, there is a need for a method for preparing quantum dot light emitting diodes in a large scale which may realize a high resolution, enhance the qualified rate and improve the utilization rate of quantum dots.